Strange appendage

[michael pierzga]

If youre doing bottom work get rid of that silly deflector. They can injure a diver and dont really work well. Best to center the rudder, completely bog fill the rudder skeg gap then epoxy the rudder to skeg. Once cured take a hack saw blade and precisely cut thru the bog to release the rudder from skeg. Work the rudder back and forth to test if your cut was perpendicular...if not fine tune. You will now have a zero tolerance gap...no rope will jam. I havent used a deflector in years. My rudder skeg tolerance is close enough to wear the antifouling .

Also add a set of flaps..port starboard..to fair in the rudder to skeg.

Kelp cutter http://www.wdschock.com/boats/schock40/kelp_b.php

[Velsia]

If it was my boat I would consider doing those things.

[michael pierzga]

Oh...

[Submarine Tom]

Leave it alone.

"If it ain't broke, don't fix it."

-Tom

[kach22i]

I agree that it is a line cutter, but I offer an alternate. It might be creating a small vortex or water flow disruption which allows some stress release at the rudder root.

Similar to this:
http://forums.pelicanparts.com/porsc...ml#post1782976

Originally Posted by rcecale

Interesting stuff about vortex generators. Here's a bit more.

Shortly after the F/A-18 was introduced into the fleet, a serious flaw was discovered in the spars that supported the vertical stabilizers.

While troubleshooting a fuel leak, one of our airframes mechanics was removed a few of the skin panels at the base of one of the verticals. What he discovered was quite scary! I'm just estimating, but there are something like 10 or 12 (maybe a few more) spars that make up the framework for the vertical. The leading spar was cracked all the way through, and the following 3 or 4 had working cracks. This thing was headed for a definite failure.

Had these spars failed, the results could/would have been loss of controlled flight. After performing fleetwide inspections of these spars, Navy and Marine Corps wide, several more similar cracks were discovered. It seems the force of impact of the airstream was just too much for these things.

The fix? You can see in this picture. We called it a LEX Fence. The leading part of the wing that came forward along the fuselage was the LEX (Leading Edge Extension) This modification was applied to all F/A-18 Hornets in the fleet, the cracked/broken spars were repared or replaced and they never returned. Apparently these fences broke the airstream up enough to relieve the stress without causing a loss of control.

Just a little FYI...


Randy

[Submarine Tom]

I agree, it's likely a line cutter BUT, usually these are reverse raked with the sharp cutting edge near the base.

-Tom

[Velsia]

I think this is most likely a deflector more than a cutter to stop weed getting between the skeg and the rudder.

[Submarine Tom]

Agreed.

-Tom

[troppo1]

maybe an old type speed log, works on pressure or vacuum